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Subject: RE: [PATCH v5 v5 1/3] eal/topology: add Topology grouping for lcores
Date: Wed, 15 Apr 2026 16:06:51 +0200
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From: =?iso-8859-1?Q?Morten_Br=F8rup?= <mb@smartsharesystems.com>
To: "Vipin Varghese" <vipin.varghese@amd.com>, <dev@dpdk.org>,
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> @@ -40,6 +45,63 @@ struct lcore_config {
>=20
>  extern struct lcore_config lcore_config[RTE_MAX_LCORE];
>=20
> +struct core_domain_mapping {
> +	rte_cpuset_t core_set;	/**< cpu_set representing lcores within
> domain */
> +	uint16_t core_count;	/**< dpdk enabled lcores within domain */
> +	uint16_t *cores;	/**< list of cores */
> +};

In Linux, rte_cpu_set_t is the same as cpu_set_t, which is limited to =
CPU_SETSIZE (1024) cores.

We should stop using that (fixed size) type, and use dynamically sized =
CPU sets instead.
Ref: https://man7.org/linux/man-pages/man3/CPU_SET.3.html

IMHO, both the fd_set type, limited to FDSET_SIZE (1024) file =
descriptors, and the cpu_set_t type, limited to CPU_SETSIZE (1024) =
cores, should be considered obsolete, and not used in new DPDK code.

It's hard to change old DPDK APIs relying on the fixed size =
rte_cpu_set_t type, but let's avoid adding new APIs using that =
(obsolete) type.

Also refer to: https://bugs.dpdk.org/show_bug.cgi?id=3D1704

PS: I guess a larger CPU_SETSIZE is available for systems built entirely =
from scratch, including libc and all libraries and applications. Not a =
generic solution.

-Morten